Method of manufacturing drawn tubing



UNITED STATES PATENT OFFICE.

WILLIAM A. MCCOOL, OF BEAVER FALLS, PENNSYLVANIA.

METHOD OF MANUFACTURING DRAWN TUBING.

SPECIFICATION formingpart of Letters Patent No. 602,416, dated April 12,1898.

Application filed September 12, 1896. Renewed March 24, 1898. Serial No.675,038. (N Sp cimen T0 (tZZ whom, it vnay concern:

Be it known that 1, WILLIAM A. MoCooL, a citizen of the United States,residing at Beaver Falls, in the county of Beaver and State ofPennsylvania, have invented certain new and useful Improvements inMethods of Manufacturing Drawn Tubing, (for all or parts of which therehave been issued to me Letters Patent in the Kingdom of Great Britainand Ireland, No. 25,686, dated November 14, 1896; in France, No.270,462, dated September 14, 1897, and in the Kingdom of Belgium, No.130,827, dated September 24, 1897;) and I do declare the following to bea full, clear, and exact description of the invention, such as willenable others skilled inthe art to which it appertains to make and usethe same.

My present invention relates to improvements in the manufacture ofcold-drawn tubing. Heretofore it has been customary in the manufactureof this class of tubing to subject the tubular blank, which hasgenerally been composed of specially-prepared steel, to the action ofacid to loosen the oxid or scale therefrom, then remove such loosescale, and subject the blank to the action of lime to prevent furtheroxidation. After this the blank is drawn over a mandrel and through adie to increase its diameter slightly, and the abovedescribed steps willbe repeated until a tube of the desired diameter is produced. Such aprocess of manufacture is objectionable, however, because of the lengthof time and expense incident to its use and because the tube could beexpanded but slightly at each passage through the die; also, the actionof the acid tends to destroy the strength of the metal and injuriouslyafiects the die and mandrel.

The object of my present improvement is to provide a method in which itwill be unnecessary to employ either lime or acid and by which arelatively larger expansion of a blank can be effected at each passagethrough the die.

In carrying out my invention I take a tubular blank which may beprepared accordin g to the manner described in my application Serial No.609,982 or other suitable manner, such blank having been annealed, andremove all scale from both exterior and interior surfaces thereof bymeans of a blast of chilled shot or similar material. This acts toremove the scale and also pitthe surfaces of the metal, so that in thesubsequent drawing the surface metal will flow more readily, and I amenabled to effect a relatively larger expansion of the tube by a singlepassage through the die than would be possible if the blank had beentreated in the manner heretofore followed. After the tube has been drawnor subjected to the action of the die and mandrel the ends thereof areplugged tightly with asbestos plugs and it is placed in anannealing-furnace. The asbestos plugs exclude air and gas from theinterior of the pipe and prevent material oxidation of the innersurface.

The steps above described are repeated until the tube has reached thedesired diameter.

From time to time during the above-described process of manufacture thetubes are washed in asoda solution to prevent the formation of rust andto remove any grit or dirt that may lodge thereon.

From the above description it will be seen that in carrying out myprocess neither acid norlime is employed at any stage, and thereby Iavoid weakening the metal being drawn, deleteriously affecting the diesand mandrels employed, &c., which, as above noted, are some of theobjectionable results of the acid processes commonly employed. Aspointed out above, also, by closing the ends of the tube to be annealeda relatively light or thin scale is formed on the inner surface of thetube during the annealing process. This is very important,as it enablesme to effectively clean the inner surface prior to any subsequentdrawing by a light blast.

While I have above described my improved process as applied to themanufacture of tubing, I am aware that it is also applicable to themanufacture of other forms.

What I claim is 1. The herein-described method of drawing metal, itconsisting in removing oxid or scale from a blank by the action of ablast charged with abrading material, in contradistinct-ion tosubjecting the blank to the action of an acid, washing the blank in asoda solution,

and subjecting the cleaned blank to the action of a draw-bench, andclosing the ends of the 10 of a draw-bench, substantially as described.blank and annealing it, substantially as de- 2. The herein-describedmethod of manuscribed. facturing drawn tubing, it consisting inre- Intestimony whereof I affix my signature moving scale fr0m both theexterior and the I in presence of two Witnesses. interior surfaces of atubular blank by the ac- WVILLIAM A. MCCOOL.

tion of a blast charged with abrading mate- Witnesses:

rial, in contradistinction t0 the use of acid, JOHN WV. CULMER,subjecting said cleaned blank to the action JAMES F. MERRIMAN.

